Fin type field effect transistors with different pitches and substantially uniform fin reveal

ABSTRACT

A semiconductor device that includes a first plurality of fin structures in a first device region and a second plurality of fin structures in a second device region. The first plurality of fin structures includes adjacent fin structures separated by a lesser pitch than the adjacent fin structures in the second plurality of fin structures. At least one layer of dielectric material between adjacent fin structures, wherein a portion of the first plurality of fin structures extending above the at least one layer of dielectric material in the first device region is substantially equal to the portion of the second plurality of fin structures extending above the at least one layer of dielectric material in the second device region. Source and drain regions are present on opposing sides of a gate structure that is present on the fin structures.

BACKGROUND Technical Field

The present disclosure relates to semiconductor devices, and moreparticularly to semiconductors including fin structures.

Description of the Related Art

With the continuing trend towards miniaturization of integrated circuits(ICs), there is a need for transistors to have higher drive currentswith increasingly smaller dimensions. The use of non-planarsemiconductor devices such as, for example, silicon fin field effecttransistors (FinFETs) may be the next step in the evolution ofcomplementary metal oxide semiconductor (CMOS) devices.

SUMMARY

In one embodiment, a method of forming fin structures is provided thatincludes forming a first plurality of fin structures in a first regionof a substrate and a second plurality of fin structures in a secondregion of a substrate, wherein a first dielectric material is presentbetween adjacent fin structures in the first plurality and secondplurality of fin structures. The first plurality of fin structures has atighter pitch than the second plurality of fin structures. The firstdielectric material is recessed so that a first portion of thedielectric material present between the fin structures in the firstplurality of fin structures is vertically offset from a second portionof the first dielectric material present between the fin structures inthe second plurality of fin structures. A first conformal etch stoplayer is deposited on exposed surfaces of the first plurality of finstructures and the second plurality of fin structures as well as theoffset upper surfaces of the first and second portions of the firstdielectric material. A second dielectric material is deposited atop thefirst conformal etch stop layer, wherein a portion of the seconddielectric material present in the second region of the substrate has anupper surface substantially coplanar with an upper surface of the firstconformal etch stop layer in the first region of the substrate. A secondconformal etch stop layer is formed on the \ second dielectric material.At least one third dielectric material layer is formed on the secondconformal etch stop layer. The at least one third dielectric material isrecessed using an etch that is selective to the first conformal etchstop layer and the second conformal etch stop layer, wherein a portionof the fin structures in the first plurality of fin structures that isrevealed by the recess etch is substantially equal to a portion of thefin structures in the second plurality of fin structures that isrevealed by the recess etch.

In another aspect of the present disclosure, a method of formingsemiconductor devices is provided. The method may include providing afirst plurality of fin structures in a first region of a substratehaving a first portion of a first dielectric material having a firstheight present between adjacent fin structures in the first region, anda second plurality of fin structures in a second region of the substratehaving a second portion of the first dielectric material having a secondheight present between adjacent fin structure in the second region. Afirst etch stop layer is deposited on the first plurality of finstructures and the second plurality of fin structures as well as offsetupper surfaces of the first and second height of the first dielectricmaterial. A second dielectric material is deposited atop the first etchstop layer, wherein a portion of the second dielectric material presentin the second region of the substrate has an upper surface substantiallycoplanar with an upper surface of the first conformal etch stop layer inthe first region of the substrate. A second conformal etch stop layer isformed on the second dielectric material, wherein a portion of thesecond etch stop layer in the second region is substantially coplanarwith a portion of the first etch stop layer in the first region. Atleast one third dielectric material layer is formed on the secondconformal etch stop layer. The at least one third dielectric material isrecessed using an etch that is selective to the first etch stop layerand the second etch stop layer, wherein a portion of the fin structuresin the first plurality of fin structures that is revealed by the recessetch is substantially equal to a portion of the fin structures in thesecond plurality of fin structures that is revealed by the recess etch.A gate structure and source and drain regions are formed on said firstand second plurality of fin structures.

In another aspect of the present disclosure, a semiconductor device isprovided. The semiconductor device comprises a first plurality of finstructures in a first device region and a second plurality of finstructures in a second device region. The first plurality of finstructures includes adjacent fin structures separated by a lesser pitchthan the adjacent fin structures in the second plurality of finstructures. At least one layer of dielectric material is present betweensaid adjacent fin structures in the first plurality of fin structures inthe first device region and the second plurality of fin structures inthe second device region. The portion of the first plurality of finstructures extending above the at least one layer of dielectric materialin the first device region is substantially equal to the portion of thesecond plurality of fin structures extending above the at least onelayer of dielectric material in the second device region. A gatestructure is present on a channel region of at least one of said firstplurality of fin structures and at least one of said second plurality offin structures. Source and drain regions are present on opposing sidesof said gate structure.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The disclosure will provide details in the following description ofpreferred embodiments with reference to the following figures wherein:

FIG. 1 is a side cross-sectional view depicting a first plurality of finstructures in a first device region and a second plurality of finstructures in a second device region, in which the first plurality offin structures has a tighter pitch than the second plurality of finstructures, in accordance with one embodiment of the present disclosure.

FIG. 2 is a side cross-sectional view depicting recessing the firstdielectric material separating adjacent fin structures, wherein aportion of first dielectric material that is recessed in the firstdevice region has an upper surface offset from the portion of the firstdielectric material that is recessed in the second device region, inaccordance with one embodiment of the present disclosure.

FIG. 3 is a side cross-sectional view depicting forming a firstconformal etch stop layer on exposed surfaces of the first plurality offin structures and the second plurality of fin structures as well as theoffset upper surfaces of the first and second portions of the firstdielectric material, in accordance with one embodiment of the presentdisclosure.

FIG. 4 is a side cross-sectional view depicting one embodiment ofdepositing a second dielectric material atop the first conformal etchstop layer, and forming a second etch stop layer on the seconddielectric material, wherein a portion of the second dielectric materialpresent in the second region of the substrate has an upper surfacesubstantially coplanar with an upper surface of the first conformal etchstop layer in the first region of the substrate, in accordance with oneembodiment of the present disclosure.

FIG. 5 is a side cross-sectional view depicting forming at least onethird dielectric material layer on the second conformal etch stop layer,in accordance with one embodiment of the present disclosure.

FIG. 6 is a side cross-sectional view depicting one embodiment ofplanarizing the dielectric material layer and stop on the hardmask.

FIG. 7 is a side cross-sectional view depicting recessing the dielectricmaterial and stop on the first conformal layer using an etch that isselective to the first conformal etch stop layer and the secondconformal etch stop layer, wherein a portion of the fin structures inthe first plurality of fin structures that is revealed by the recessetch is substantially equal to a portion of the fin structures in thesecond plurality of fin structures that is revealed by the recess etch,in accordance with one embodiment of the present disclosure.

FIG. 8 is a side cross-sectional view depicting removing the exposedportion of the first and second etch stop layers, in accordance with oneembodiment of the present disclosure.

FIG. 9 is a side cross-sectional view of a removing the first etch stoplayer 35 from the second region 30 of the substrate 5 that is depictedin FIG. 4, in accordance with one embodiment of the present disclosure.

FIG. 10 is a side cross-sectional view depicting one embodiment ofdepositing a second dielectric material in the first region and thesecond region of the structure depicted in FIG. 9, and forming a secondconformal etch stop layer on the second dielectric material, wherein aportion of the second dielectric material present in the second regionof the substrate has an upper surface substantially coplanar with anupper surface of the first conformal etch stop layer in the first regionof the substrate, in accordance with one embodiment of the presentdisclosure.

FIG. 11 is a side cross-sectional view depicting planarizing thestructure depicted in FIG. 10.

FIG. 12 is a side cross sectional view depicting recessing thedielectric material using an etch that is selective to the firstconformal etch stop layer and the second conformal etch stop layer,wherein a portion of the fin structures in the first plurality of finstructures that is revealed by the recess etch is substantially equal toa portion of the fin structures in the second plurality of finstructures that is revealed by the recess etch, in accordance with oneembodiment of the present disclosure.

FIG. 13 is a side cross-sectional view depicting removing the first andsecond etch stop layers, in accordance with one embodiment of thepresent disclosure.

FIG. 14 is a side cross-sectional view depicting one embodiment offorming a gate structure on the channel region of the fin structuresdepicted in FIG. 7.

FIG. 15 is a top down view depicting forming source and drain regions onthe source and drain portions of the fin structures that are on opposingsides of the gate structure.

DETAILED DESCRIPTION

Detailed embodiments of the claimed methods and structures are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely illustrative of the claimed structures and methods that maybe embodied in various forms. In addition, each of the examples given inconnection with the various embodiments is intended to be illustrative,and not restrictive. Further, the figures are not necessarily to scale,some features may be exaggerated to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the methods and structures of the present disclosure.

Reference in the specification to “one embodiment” or “an embodiment” ofthe present principles, as well as other variations thereof, means thata particular feature, structure, characteristic, and so forth describedin connection with the embodiment is included in at least one embodimentof the present principles. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment”, as well any other variations,appearing in various places throughout the specification are notnecessarily all referring to the same embodiment. For purposes of thedescription hereinafter, the terms “upper”, “over”, “overlying”,“lower”, “under”, “underlying”, “right”, “left”, “vertical”,“horizontal”, “top”, “bottom”, and derivatives thereof shall relate tothe embodiments of the disclosure, as it is oriented in the drawingfigures. The term “positioned on” means that a first element, such as afirst structure, is present on a second element, such as a secondstructure, wherein intervening elements, such as an interface structure,e.g. interface layer, may be present between the first element and thesecond element. The term “direct contact” means that a first element,such as a first structure, and a second element, such as a secondstructure, are connected without any intermediary conducting, insulatingor semiconductor layers at the interface of the two elements.

The structures and methods that are disclosed herein provide etch stoplayers that are positioned to control the amount, i.e., height, of finstructures that extends above the dielectric material that isolatesadjacent fin structures from one another, in which the fin structuresinclude a first plurality having a first pitch and a second pluralityhaving a second pitch, in which the first pitch is tighter than thesecond pitch.

In FINFET technology, Fin reveal can be an important step which definesthe Fin height. The micro-loading effects that result from increasesscaling of FinFET devices can lead to FIN reveal variation betweenpatterning dense and isolated features on FinFET device. Insufficientand/or excessive FIN reveal can impact device yield and device step-upfor FinFET structures. In some scenarios, there is an eager demand foralleviating Fin reveal variation at various device/pattern densityareas.

The methods and structures disclosed herein resolve the issues of havingnon-uniform Fin reveal between patterning dense and isolated deviceareas. In some embodiments, the etch stop layers used to control the finreveal includes a first etch stop layer, e.g., a nitride liner depositedby plasma enhanced chemical vapor deposition or high density plasmachemical vapor deposition, atop the STI region that helps to define theFIN height of the fin structures having the tighter pitch, i.e., thedandified device area, in which the first etch stop layer can alsoprovide a mechanism for interlevel dielectric layer (ILD) oxide recessstop control in downstream process steps. In some embodiments, a secondetch stop layer, which may be referred to as an embedded nitride linerdeposited by plasma enhanced chemical vapor deposition (PECVD), ispresent in the isolated area and provides interlevel dielectric layer(ILD) oxide recess stop control in the region of the substrate havingthe large features with the great pitch dimension separating adjacentfin structures. The aforementioned first and second etch stop layershelp minimize the FIN Reveal variations that typically occur in priorprocess flows that include fin structures having density variations,i.e., variations in fin pitch. In some embodiments, a similarintegration scheme could be applied multiply to eliminate the macro tomacro fin reveal variations due to various pattern densities. Furtherdetails regarding the method and structures of the present disclosureare now described with reference to FIGS. 1-15.

FIG. 1 depicts a first plurality of fin structures 10 in a first deviceregion 20 and a second plurality of fin structures 15 in a second deviceregion 25, in which the first plurality of fin structures 10 has atighter pitch P1 than the second plurality of fin structures 15. As usedherein, the term “fin structure” refers to a semiconductor material,which can be employed as the body of a semiconductor device, in whichthe gate structure is positioned around the fin structure such thatcharge flows down the channel on the two sidewalls of the fin structureand optionally along the top surface of the fin structure. The finstructures 10, 15 present in the first and second device regions 20, 25are processed to provide FinFETs. A field effect transistor (FET) is asemiconductor device in which output current, i.e., source-draincurrent, is controlled by the voltage applied to a gate structure to thechannel of a semiconductor device. A finFET is a semiconductor devicethat positions the channel region of the semiconductor device in a finstructure. As used herein, the term “drain” means a doped region insemiconductor device located at the end of the channel region, in whichcarriers are flowing out of the transistor through the drain. The term“source” is a doped region in the semiconductor device, in whichmajority carriers are flowing into the channel region. The source anddrain regions of a finFET are typically formed on source and drainportions of the fin structures that are on opposing sides of the portionof the fin structure containing the channel region. In some examples,epitaxial semiconductor material provides portions of the source anddrains regions of the FinFET, in which the epitaxial semiconductormaterial is formed on a portion of the source and drain portions of thefin structure.

The semiconductor material that provides the fin structures 10, 15 maybe a semiconducting material including, but not limited to silicon,strained silicon, a silicon carbon alloy (e.g., silicon doped withcarbon (Si:C), silicon germanium, a silicon germanium and carbon alloy(e.g., silicon germanium doped with carbon (SiGe:C), silicon alloys,germanium, germanium alloys, gallium arsenic, indium arsenic, indiumphosphide, as well as other III/V and II/VI compound semiconductors. Inone example, the fin structures 10 that are present in the first deviceregion 20 are composed of a different semiconductor material than thefin structures 15 that are present in the second device region 25. Inanother example, the fin structures 10 that are present in the firstdevice region 20 are composed of the same semiconductor material thatthe fin structures 15 that are present in the second device region 25are composed of.

The plurality of fin structures 10 may be formed from a semiconductorsubstrate 5, using deposition photolithography and etch processes. Inthe example, in which the substrate 5 is a bulk substrate, an upperportion of the substrate 5 may be provide the material for the secondplurality of fin structures 15 that are defined by etching. The firstplurality of the fin structures 10 may be provided may a semiconductormaterial layer 6 that is present on the upper surface of thesemiconductor substrate 5. The semiconductor material layer 6 may becomposed of the same or a different composition as the substrate 5. Insome embodiments, when the semiconductor material layer 6 is composed ofa different composition as the substrate 5, the composition of thesemiconductor material 6 may be selected to provide a strain thatresults from a difference in lattice dimension between an epitaxiallyformed semiconductor material layer 6 and the semiconductor substrate 5.For example, when the first region of the substrate 20 is processed toprovide p-type FinFETs, the semiconductor material layer 6 can beselected to be composed of silicon germanium or germanium epitaxiallygrown on a silicon substrate to produce an intrinsic compressive stressthat produces carrier speed enhancements in p-type semiconductordevices. In another example, when the first region of the substrate 20is processed to provide n-type FinFETs, the semiconductor material layer6 can be selected to be composed of silicon doped with carbonepitaxially grown on a silicon substrate to produce an intrinsic tensilestress that produces carrier speed enhancements in n-type semiconductordevices.

The fin structures 10, 15 are typically formed using deposition,photolithography, i.e., patterning, and etch processes. In oneembodiment, the patterning process used to define each of the finstructures 10, 15 is a sidewall image transfer (SIT) process. The SITprocess can include forming a first mandrel material layer (not shown)on the material layer that provides the fin structures 10, 15, such asupper surface of the substrate 5 and the semiconductor material layer 6.The first mandrel material layer can include any material(semiconductor, dielectric or conductive) that can be selectivelyremoved from the structure during a subsequently performed etchingprocess. In one embodiment, the first mandrel material layer may becomposed of amorphous silicon or polysilicon. In another embodiment, thefirst mandrel material layer may be composed of a metal, such as, e.g.,aluminum (Al), tungsten (W), or copper (Cu). The first mandrel materiallayer can be formed by a deposition method, such as chemical vapordeposition or plasma enhanced chemical vapor deposition. In oneembodiment, the thickness of the first mandrel material layer can befrom 50 nm to 300 nm. Following deposition of the first mandrel materiallayer, the first mandrel material layer can be patterned by lithographyand etching to form a plurality of first mandrel structures on thetopmost surface of the semiconductor containing material that providesthe fin structures 10, 15 e.g., the upper surface of the substrate 5 orthe upper surface of the semiconductor material layer 6.

In some embodiments, the SIT process may continue by forming adielectric spacer on each sidewall of each of the first mandrelstructures. The dielectric spacer can be formed by deposition of adielectric spacer material, and then etching the deposited dielectricspacer material. The dielectric spacer material may comprise anydielectric spacer material such as, for example, silicon dioxide,silicon nitride or a dielectric metal oxide. Examples of depositionprocesses that can be used in providing the dielectric spacer materialinclude, but are not limited to, chemical vapor deposition (CVD), plasmaenhanced chemical vapor deposition (PECVD), or atomic layer deposition(ALD). Examples of etching that be used in providing the dielectricspacers include any etching process such as, e.g., reactive ion etching(RIE). Since the dielectric spacers are used in the SIT process as anetch mask, the width of the each dielectric spacer determines the widthof each fin structure 10, 15.

In some embodiments, after formation of the dielectric spacers, the SITprocess continues by removing each the first mandrel structure. Each ofthe first mandrel structures can be removed by an etching process thatis selective for removing the mandrel material as compared tosemiconductor material of the substrate 5 or the semiconductor materiallayer 6 that provides the fin structures 10, 15, e.g., silicon (Si).Following the first mandrel structure removal, the SIT process continuesby transferring the pattern provided by the dielectric spacers into thesemiconductor material layer that provides the fin structures 10, 15.The pattern transfer may be achieved by utilizing at least one etchingprocess that can include dry etching, such as reactive ion etching(RIE), plasma etching, ion beam etching or laser ablation, chemical wetetch processes or a combination thereof. In one example, the etchprocess used to transfer the pattern may include one or more reactiveion etching (RIE) steps. Following etching, i.e., pattern transfer, theSIT process may conclude with removing the dielectric spacers using anetch process or a planarization process.

In some embodiments, the fin structures 10 in the first plurality of finstructures 10 are grouped in a denser, i.e., tighter pitch arrangement,than the fin structures 15 in the second plurality of fin structures 15.As used herein, the “pitch” is the center to center distance separatingadjacent fin structures having a parrallel length.

The height H1 of the fin structures in the first plurality of finstructures 10 is measured from the upper surface of the portions of thesemiconductor material layer 6 that have been recessed, and the heightof the fin structures in the first plurality of fin structures 10 isgenerally less than the height of the fin structures in the secondplurality of fin structures 20. In one embodiment, each of the pluralityof fin structures 10 has a height H1 ranging from 10 nm to 100 nm. Inone example, each of the plurality of fin structures 10 has a height H1ranging from 20 nm to 50 nm. Each of the plurality of fin structures 10may have a width W1 of less than 20 nm. In another embodiment, each ofthe plurality of fin structures 10 has a width W1 ranging from 3 nm to 8nm. Although four fin structures are depicted in FIG. 1, the presentdisclosure is not limited to only this example. It is noted that anynumber of fin structures 10 may be in the first plurality of finstructures 10 that are present on the substrate 5. The pitch P1separating adjacent fin structures 10 may range from 35 nm to 45 nm. Inanother example, the pitch P1 separating adjacent fin structures 10 mayrange from 30 nm to 40 nm. It is noted that the above examples for pitchare provided for illustrative purposes only, and that any pitch may beused with the methods and structures of the present disclosure includinga pitch P1 below 30 nm.

The height H2 of the fin structures in the second plurality of finstructures 15 is measured from the upper surface of the portions of thesemiconductor substrate 5 that have been recessed, and the height of thefin structures in the first plurality of fin structures 15 is generallygreater than the height of the fin structures in the first plurality offin structures 10. In one embodiment, each of the plurality of finstructures 15 has a height H2 ranging from 10 nm to 100 nm. In oneexample, each of the plurality of fin structures 15 has a height H2ranging from 20 nm to 50 nm. Each of the plurality of fin structures 15may have a width W2 of less than 20 nm. In another embodiment, each ofthe plurality of fin structures 15 has a width W2 ranging from 3 nm to 8nm. Although only one fin structure are depicted in FIG. 1, the presentdisclosure is not limited to only this example. It is noted that anynumber of fin structures 15 may be in the first plurality of finstructures 15 that are present on the substrate 5. The pitch P2separating adjacent fin structures 15 in the second plurality of finstructures 15 may range from 10 nm to 500 nm. In another example, thepitch P2 separating adjacent fin structures in the second plurality offin structures 15 may range from 20 nm to 100 nm.

Still referring to FIG. 1, in some embodiments, the space between theadjacent fin structures 10, 15 is filled with at least one dielectricmaterial 30 a, 30 b, 31 that provides for device isolation betweenadjacent fin structures 10, 15. Forming the at least one dielectricmaterial 30 a, 30 b, 31 may begin with forming a liner dielectric 31 onthe surfaces of the fin structures 10, 15, and the recessed surface ofthe semiconductor layer 6 and the substrate 5. The liner dielectric 31may be composed of a nitride, oxide or oxynitride material. In someembodiments, the liner dielectric may be composed of silicon oxide orsilicon nitride. The liner dielectric 31 is typically formed using aconformal deposition process. The term “conformal” denotes a layerhaving a thickness that does not deviate from greater than or less than30% of an average value for the thickness of the layer. The linerdielectric 31 may be formed using a deposition process, such as chemicalvapor deposition, or the liner dielectric 31 may be formed using agrowth process, such as thermal oxidation.

Still referring to FIG. 1, after forming the liner dielectric 31, afirst dielectric material 30 a, 30 b is deposited filling the spacebetween adjacent fin structures 10, 15. The first dielectric material 30a, 30 b may be composed of a nitride, oxide, oxynitride material, and/orany other suitable dielectric layer. For example, when the firstdielectric material 30 a, 30 b is composed of an oxide, the firstdielectric material 30 a, 30 b can be silicon oxide (SiO₂). In anotherexample, when the first dielectric material 30 a, 30 b is composed of anitride, the dielectric regions can be silicon nitride. The firstdielectric material 30 a, 30 b can be formed by a deposition process,such as CVD. Variations of CVD processes include, but not limited to,Atmospheric Pressure CVD (APCVD), Low Pressure CVD (LPCVD) and PECVD,Metal-Organic CVD (MOCVD) and combinations thereof. Alternatively, thefirst dielectric material 30 a, 30 b may be deposited using spin ondeposition, and deposition from solution.

FIG. 2 depicts one embodiment of recessing the first dielectric material30 a, 30 b separating adjacent fin structures 10, 15, wherein a portionof first dielectric material 30 a that is recessed in the first deviceregion 20 has an upper surface offset from the portion of the firstdielectric material 30 b that is recessed in the second device region25. It is noted that the portion of the first dielectric material 30 bthat is present in the second region 25 of the substrate that isseparating the second plurality of fin structures 15, which areseparated by the greater pitch, i.e., a looser pitched/less denseplurality of fin structures, than the first plurality of fin structures10 in the first region 20 is etched at a greater rate than the portionof the first dielectric material 30 b that is present in the firstregion 20 of the substrate 5 between the adjacent fin structures in thetighter pitched/greater density first plurality of fin structures 10.This results in a vertical offset L1 between the recessed upper surfaceof the first dielectric material 30 a in the first device region 20 ofthe substrate 5 and the recessed upper surface of the second dielectricmaterial 30 b in the second device region 25 of the substrate 5. Thevertical offset L1 may range from 5 nm to 100 nm. In other embodiments,the vertical offset L1 may range from 100 nm to 1 micron.

The first dielectric material 30 a, 30 b may be recessed using aselective etch process to provide an exposed portion, i.e., revealportion, of the upper portion of the fin structures 15, 20. In someembodiments, the dielectric regions are removed by an etch that isselective to the dielectric cap 11, 16 that is present on the finstructures 15, 20. The etch process may also remove the dielectric liner31. In some embodiments, this can be done using hot phosphorus. In thisexample, the etch process for recessing the first dielectric material 30a, 30 b may be selective to the fin structures 10, 15. The etch processfor recessing the first dielectric material 30 a, 30 b may be ananisotropic etch or an isotropic etch. In some examples, the etchprocess may be a wet chemical etch, reactive ion etch (RIE), plasmaetch, laser etch and combinations thereof.

FIG. 3 depicts forming a first etch stop layer 35 on the surfaces of thefirst plurality of fin structures 10 and the second plurality of finstructures 15 as well as the offset upper surfaces of the first andsecond portions of the first dielectric material 30 a, 30 b. The firstetch stop layer 35 may be a conformal layer. The first etch stop layer35 can help to define the fin reveal height H3 in the first region 20 ofthe substrate 5, in which the first plurality of fin structures 10having a tight pitch P1 (high density) is present. The first etch stoplayer 35 can also provide an interlevel dielectric layer (ILD) etch stoplayer for recess control in downstream processes.

In some embodiments, the first etch stop layer 35 is composed of anitride dielectric, such as silicon nitride. It is noted that this isonly one example of a composition that is suitable for the first etchstop layer 35. The first etch stop layer 35 may be composed of anydielectric layer that can protect, via selective etch resistance, theunderlying first dielectric material 30 a in the first device region 20during subsequent processing of semiconductor devices using the firstplurality of fin structures 10. The first etch stop layer 35 may bedeposited using chemical vapor deposition. The first etch stop layer 35is typically formed using a conformal deposition process. Suitableexamples of chemical vapor deposition for forming the first etch stoplayer 35 include plasma enhanced chemical vapor deposition (PECVD) andhigh density plasma chemical vapor deposition (HDPCVD). The first etchstop layer 35 typically has a thickness ranging from 1 nm to 10 nm. Insome embodiments, the first etch stop layer 35 has a thickness rangingfrom 2 nm to 5 nm.

FIG. 4 depicts one embodiment of depositing a second dielectric material40 a, 40 b atop the first etch stop layer 35, and forming a second etchstop layer 45 on the second dielectric material 40. In some embodiments,the portion of the second etch stop layer 45 that is present in thesecond region 25 of the substrate 5 provides an interlevel dielectric(ILD) oxide recess stop control layer, which controls the recess depthof the dielectric material separating the adjacent fin structures in thesecond plurality of fin structures 15. The upper surface of the secondetch stop layer 45 in the second region 25 of the substrate 5 issubstantially coplanar with the upper surface of the first etch stoplayer 35 in the first region 20. When the upper surface of the finstructures 10 in the first region 20 is coplanar with the upper surfaceof the fin structures 15 in the second region 25, the coplanar first andsecond etch stop layers 35, 45 provide a grouping of etch stops thatprovide a uniform reveal height for the first plurality of finstructures 10 and the second plurality of fin structures 15.

The second dielectric material 40 a, 40 b is similar to the firstdielectric material 30 a, 30 b. The first dielectric material 40 a, 40 bmay be composed of a nitride, oxide, oxynitride material, and/or anyother suitable dielectric layer. For example, when the second dielectricmaterial 40 a, 40 b is composed of an oxide, the second dielectricmaterial 40 a, 40 b can be silicon oxide (SiO₂). In another example,when the second dielectric material 40 a, 40 b is composed of a nitride,the dielectric regions can be silicon nitride. The second dielectricmaterial 40 a, 40 b can be formed by a deposition process, such as CVD.Variations of CVD processes include, but not limited to, AtmosphericPressure CVD (APCVD), Low Pressure CVD (LPCVD) and PECVD, Metal-OrganicCVD (MOCVD) and combinations thereof. Alternatively, the seconddielectric material 40 a, 40 b may be deposited using spin ondeposition, and deposition from solution.

The deposition process for forming the second dielectric material 40 a,40 b continues until the portion of the second dielectric layer 40 bthat is present in the second region 25 has an upper surface that issubstantially coplanar with the upper surface of the portion of thefirst etch stop layer 35 in the first region 20.

In some embodiments, the second etch stop layer 45 is composed of anitride dielectric, such as silicon nitride. It is noted that this isonly one example of a composition that is suitable for the second etchstop layer 45. The second etch stop layer 45 may be composed of anydielectric layer that can protect, via selective etch resistance, theunderlying second dielectric material 40 b in the second device region25 during subsequent processing of semiconductor devices using thesecond plurality of fin structures 15. The second etch stop layer 45 maybe deposited using chemical vapor deposition. The second etch stop layer45 is typically formed using a conformal deposition process. Suitableexamples of chemical vapor deposition for forming the second etch stoplayer 45 include plasma enhanced chemical vapor deposition (PECVD) andhigh density plasma chemical vapor deposition (HDPCVD). The second etchstop layer 45 typically has a thickness ranging from 1 nm to 10 nm. Insome embodiments, the second etch stop layer 45 has a thickness rangingfrom 2 nm to 5 nm.

FIG. 5 depicts forming at least one third dielectric material layer 50on the second etch stop layer 45. The third dielectric material 50 maybe composed of a nitride, oxide, oxynitride material, and/or any othersuitable dielectric layer. For example, when the third dielectricmaterial 50 is composed of an oxide, the third dielectric material 50can be silicon oxide (SiO₂). In another example, when the thirddielectric material layer 50 is composed of a nitride, the dielectricregions can be silicon nitride. The third dielectric material layer 50can be formed by a deposition process, such as CVD. Variations of CVDprocesses include, but not limited to, Atmospheric Pressure CVD (APCVD),Low Pressure CVD (LPCVD) and PECVD, Metal-Organic CVD (MOCVD) andcombinations thereof. Alternatively, the third dielectric material layer50 may be deposited using spin on deposition, and deposition fromsolution. The thickness of the at least one third dielectric materiallayer 50 is selected so that the upper surface of the at least one thirddielectric material layer 50 is substantially coplanar with the uppersurfaces of the first and second plurality of fin structures 15, 20. Thethickness of the third dielectric material layer 50 can be overdeposited to extend above the upper surfaces of the first and secondplurality of fin structure 15, 25, as depicted in FIG. 5

FIG. 6 depicts one embodiment of planarizing the at least one thirddielectric material layer 50 that is depicted in FIG. 5 so that theupper surfaces of the planarized third dielectric material layer 50, andthe first and second plurality of fin structures are substantiallycoplanar. The planarization process may be provided by chemicalmechanical planarization (CMP). Other planarization process may includegrinding and polishing.

FIG. 7 depicts one embodiment of recessing the at least one thirddielectric material layer 50 using an etch that is selective to thefirst etch stop layer 35 and the second etch stop layer 45, wherein aportion H3 of the fin structures 10 in the first plurality of finstructures 10 that is revealed by the recess etch is substantially equalto a portion H4 of the fin structures 15 in the second plurality of finstructures 15 that is revealed by the recess etch.

As used herein, the term “selective” in reference to a material removalprocess denotes that the rate of material removal for a first materialis greater than the rate of removal for at least another material of thestructure to which the material removal process is being applied. Forexample, in one embodiment, a selective etch may include an etchchemistry that removes a first material selectively to a second materialby a ratio of 10:1 or greater, e.g., 100:1 or greater, or 1000:1 orgreater.

In one embodiment, the high-k dielectric fin liner 25 that is present inthe first device region 15 is removed by an etch that is selective to atleast the fin structures 10 and the block mask 30. In some embodiments,when the third dielectric material layer 50 is composed of an oxide,such as silicon oxide, and the first etch stop layer 35 and the secondetch stop layer 45 are composed of a nitride, such as silicon nitride,the selective etch may remove the oxide material without significantlydamaging the nitride material. The etch process for recessing the thirddielectric material 50 may be an anisotropic etch, such as reactive ionetch, or an isotropic etch, such as a wet chemical etch.

FIG. 8 depicts one embodiment of removing the exposed portion of thefirst and second etch stop layers 35, 45. In some embodiments, the firstand second etch stop layers 35, 45 are removed by an etch that isselective to the fin structures 10, 15. The etch process for removingthe first and second etch stop layer 35, 45 may also remove thedielectric caps 11, 16 that are present on the first and secondplurality of fin structures 10, 15. The etch process for recessing thethird dielectric material 50 may be an anisotropic etch, such asreactive ion etch, or an isotropic etch, such as a wet chemical etch.

Following removal of the first and second etch stop layers 35, 45, thefirst plurality of fin structures 10 and the second plurality of finstructures 15 may be further processed to provide semiconductor devices.The portion (also referred to as first revealed portion) of the firstplurality of fin structures 10 extending above the remaining portion ofthe first dielectric material 30 a in the first device region 10 issubstantially equal to the portion (also referred to as second revealedportion) of the second plurality of fin structures 15 extending abovethe remaining portion of the second dielectric material 40 b in thesecond device region 25. For example, the height H3 of the first revealportion for the first fin structures 10 is equal to the height H4 of thesecond reveal portion for the second fin structures 15, in which theheight H3, H4 of the first and second reveal portion may each rangingfrom 50 nm to 100 nm. In another example, the height H3 of the firstreveal portion for the first fin structures 10 is equal to the height H4of the second reveal portion for the second fin structures 15, in whichthe height H3, H4 of the first and second reveal portion may eachranging from 10 nm to 50 nm.

It is noted that the embodiment that is described with reference toFIGS. 1-8 is only one embodiment of the present disclosure and it is notintended that the present disclosure be limited to only this disclosure.For example, FIGS. 9-15 illustrate another embodiment of the presentdisclosure, in which the first etch stop layer 35 is removed from theportion of the substrate that includes the less dense/greater pitchedfin structures, i.e., the second region 25 of the substrate 5.

FIG. 9 depicts one embodiment of removing the first etch stop layer 35from the second region 25 of the substrate 5 that is depicted in FIG. 4.The first etch stop layer 35 remains in the first region 20 of thesubstrate 5. To provide that the first etch stop layer 35 is onlyremoved from the second region 25 of the substrate 5, an etch mask, suchas a photoresist mask (not shown) may be formed over the first region 20of the substrate 5, and the portion of the first etch stop layer 35 thatis exposed in the second region 25 is removed using an etch that isselective to the photoresist mask and the first dielectric material 30b. The etch mask may be formed using deposition, photolithography anddevelopment process steps. After removing the portion of the first etchstop layer 35 from the second region 25 of the substrate, the etch mask,e.g., photoresist mask, may be removed.

FIG. 10 depicts one embodiment of depositing a second dielectricmaterial 40 in the first region 20 and the second region 25 of thesubstrate 5 depicted in FIG. 9, and forming a second conformal etch stoplayer 45 on the second dielectric material 40. The second dielectricmaterial 40 that is depicted in FIG. 10 is similar to the seconddielectric material 40 a, 40 b that is described above with reference toFIG. 4 with the exception that in the embodiment depicted in FIG. 10 thesecond dielectric material 40 is formed in direct contact with theportion of the first dielectric material 30 b that is present in thesecond region 25 of the substrate 5. Therefore, the above description ofthe second dielectric material 40 a, 40 b that is described above withreference to FIG. 4 is suitable for describing at least one embodimentof the second dielectric material 40 that is depicted in FIG. 10. In oneembodiment, the portion of the second dielectric material 40 that ispresent in the second region 20 of the substrate 5 has an upper surfacesubstantially coplanar with an upper surface of the first etch stoplayer 35 in the first region 20 of the substrate 5.

FIG. 10 also depicts forming a second etch stop layer 45 on the seconddielectric material 40. The second etch stop layer 45 that is depictedin FIG. 10 is similar to the second etch stop layer 45 that is depictedin FIG. 4. Therefore, the above description of the second etch stoplayer 45 that is described above with reference to FIG. 4 is suitablefor describing at least one embodiment of the second etch stop layer 45that is depicted in FIG. 10. In one embodiment, the portion of thesecond etch stop layer 45 that is present in the second region 20 of thesubstrate 5 has an upper surface substantially coplanar with an uppersurface of the first etch stop layer 35 in the first region 20 of thesubstrate 5.

FIG. 11 depicts one embodiment of depositing a third dielectric material50 on the structure depicted in FIG. 10 followed by applyingplanarization step. The third dielectric material 50 is formed atop thesecond etch stop layer 45. The third dielectric material 50 may becomposed of a nitride, oxide, oxynitride material, and/or any othersuitable dielectric layer. For example, when the third dielectricmaterial 50 is composed of an oxide, the third dielectric material 50can be silicon oxide (SiO₂). In another example, when the thirddielectric material layer 50 is composed of a nitride, the dielectricregions can be silicon nitride. The third dielectric material layer 50can be formed by a deposition process, such as CVD. Variations of CVDprocesses include, but not limited to, Atmospheric Pressure CVD (APCVD),Low Pressure CVD (LPCVD) and PECVD, Metal-Organic CVD (MOCVD) andcombinations thereof. Alternatively, the third dielectric material layer50 may be deposited using spin on deposition, and deposition fromsolution. The thickness of the at least one third dielectric materiallayer 50 is selected so that the upper surface of the at least one thirddielectric material layer 50 is substantially coplanar with the uppersurfaces of the first and second plurality of fin structures 15, 20. Thethickness of the third dielectric material layer 50 can be overdeposited to extend above the upper surfaces of the first and secondplurality of fin structure 15, 25.

FIG. 11 also depicts one embodiment of planarizing the at least onethird dielectric material layer 50 so that the upper surfaces of theplanarized third dielectric material layer 50, and the first and secondplurality of fin structures 10, 15 are substantially coplanar. Theplanarization process may be provided by chemical mechanicalplanarization (CMP). Other planarization process may include grindingand polishing.

FIG. 12 depicts one embodiment removing the at least one thirddielectric material 50 in the second region 25 and the portion of thesecond dielectric material 40 a in the first region 20 using a recessetch that is selective to the first etch stop layer 35 and the secondetch stop layer 45, wherein a portion of the fin structures in the firstplurality of fin structures that is revealed by the recess etch issubstantially equal to a portion of the fin structures in the secondplurality of fin structures that is revealed by the recess etch. Therecess etch that is depicted in FIG. 12 has been described above withreference to FIG. 8. Therefore, the recess etch that is described inFIG. 8 is suitable for describing at least one embodiment of the recessetch for revealing the fin structures that is depicted in FIG. 12. FIG.13 depicts removing the exposed portions of the first and second etchstop layers 35, 45. The first and second etch stop layers 35, 45 may beremoved by an etch that is selective to the fin structures 10, 15.

Following removal of the first and second etch stop layers 35, 45, thefirst plurality of fin structures 10 and the second plurality of finstructures 15 may be further processed to provide semiconductor devices.The portion (also referred to as first revealed portion) of the firstplurality of fin structures 10 extending above the remaining portion ofthe first dielectric material 30 a in the first device region 10 issubstantially equal to the portion (also referred to as second revealedportion) of the second plurality of fin structures 15 extending abovethe remaining portion of the second dielectric material 40 b in thesecond device region 25. For example, the height H3 of the first revealportion for the first fin structures 10 is equal to the height H4 of thesecond reveal portion for the second fin structures 15, in which theheight H3, H4 of the first and second reveal portion may each rangingfrom 50 nm to 100 nm. In another example, the height H3 of the firstreveal portion for the first fin structures 10 is equal to the height H4of the second reveal portion for the second fin structures 15, in whichthe height H3, H4 of the first and second reveal portion may eachranging from 10 nm to 50 nm.

As noted above, the method for forming the fin structures 10, 15depicted in FIGS. 1-13 can be used for forming FinFET semiconductordevices. To provide FinFET semiconductor devices for the fin structures10, 15 formed using the method described with reference to FIGS. 1-13,the method may continue with forming a gate structure for each of thefin structures 10, 15 that will provide a semiconductor device. FIG. 14depicts forming a gate structure 60 on the fin structures 10, 15 thatare depicted in FIG. 7. It is noted that the gate structure 60 that isdepicted in FIG. 14 as being formed on the fin structures 10, 15depicted in FIG. 7 may equally be formed on the fin structures 10, 15that are depicted in FIG. 13.

The “gate structure” functions to switch the semiconductor device froman “on” to “off” state, and vice versa. The gates structure 60 is formedon the channel region of the fin structures 10, 15. The gate structure60 typically includes at least a gate dielectric 61 that is present onthe channel region of the fin structure 10, 15 and a gate electrode 62that is present on the gate dielectric 61. In one embodiment, the atleast one gate dielectric layer 61 includes, but is not limited to, anoxide, nitride, oxynitride and/or silicates including metal silicates,aluminates, titanates and nitrides. In one example, when the at leastone gate dielectric layer 61 is comprised of an oxide, the oxide may beselected from the group including, but not limited to, SiO₂, HfO₂, ZrO₂,Al₂O₃, TiO₂, La₂O₃, SrTiO₃, LaAlO₃, Y₂O₃ and mixture thereof. Thephysical thickness of the at least one gate dielectric layer 61 mayvary, but typically, the at least one gate dielectric layer 61 has athickness from 1 nm to 10 nm. In another embodiment, the at least onegate dielectric layer 61 has a thickness from 1 nm to 3 nm.

The conductive material of the gate electrode 62 may comprisepolysilicon, SiGe, a silicide, a metal or a metal-silicon-nitride suchas Ta—Si—N. Examples of metals that can be used as the gate electrode 62include, but are not limited to, Al, W, Cu, and Ti or other likeconductive metals. The layer of conductive material for the gateelectrode 62 may be doped or undoped. If doped, an in-situ dopingdeposition process may be employed. Alternatively, a doped conductivematerial can be formed by deposition, ion implantation and annealing.The gate structures may also be formed using sidewall image transfer(SIT).

FIG. 15 depicts one embodiment of forming source and drain regions 65 a,65 b on the source and drain portions of the fin structures 10, 15 thatare on opposing sides of the gate structure 60. Forming the source anddrain regions 65 a, 65 b may include forming an in situ doped epitaxialsemiconductor material on the source and drain region portions of thefin structures 10, 15. The term “epitaxial semiconductor material”denotes a semiconductor material that has been formed using an epitaxialdeposition or growth process. “Epitaxial growth and/or deposition” meansthe growth of a semiconductor material on a deposition surface of asemiconductor material, in which the semiconductor material being grownhas substantially the same crystalline characteristics as thesemiconductor material of the deposition surface. In some embodiments,when the chemical reactants are controlled and the system parameters setcorrectly, the depositing atoms arrive at the deposition surface withsufficient energy to move around on the surface and orient themselves tothe crystal arrangement of the atoms of the deposition surface. Thus, insome examples, an epitaxial film deposited on a {100} crystal surfacewill take on a {100} orientation. In some embodiments, the epitaxialdeposition process is a selective deposition method, in which theepitaxial semiconductor material is formed only on semiconductormaterial deposition surfaces. The epitaxial deposition process will notform epitaxial semiconductor material on dielectric surfaces.

In some embodiments, the epitaxial semiconductor material that providesthe source and drain regions 65 a, 65 b may be composed of silicon (Si),germanium (Ge), silicon germanium (SiGe), silicon doped with carbon(Si:C) or a combination thereof. In one example, the p-type source anddrain regions are provided by silicon germanium (SiGe) epitaxialsemiconductor material. In one embodiment, a number of different sourcesmay be used for the epitaxial deposition of the epitaxial semiconductormaterial that provides the source and drain regions 65 a, 65 b. Examplesof silicon including source gasses may include silane, disilane,trisilane, tetrasilane, hexachlorodisilane, tetrachlorosilane,dichlorosilane, trichlorosilane, methylsilane, dimethylsilane,ethylsilane, methyldisilane, dimethyldisilane, hexamethyldisilane andcombinations thereof. Examples of germanium including source gasses forepitaxially forming the epitaxial semiconductor material of a germaniumcontaining semiconductor include germane, digermane, halogermane,dichlorogermane, trichlorogermane, tetrachlorogermane and combinationsthereof. Epitaxial deposition may be carried out in a chemical vapordeposition apparatus, such as a metal organic chemical vapor deposition(MOCVD) apparatus or a plasma enhanced chemical vapor deposition (PECVD)apparatus. The temperature for epitaxial deposition typically rangesfrom 550° C. to 900° C. Although higher temperature typically results infaster deposition, the faster deposition may result in crystal defectsand film cracking.

The epitaxial semiconductor material that provides the source and drainregions 65 a, 65 b may be in situ doped to a p-type conductivity or ann-type conductivity. The term “in situ” denotes that a dopant, e.g.,n-type or p-type dopant, is introduced to the base semiconductormaterial, e.g., silicon or silicon germanium, during the formation ofthe base material. For example, an in situ doped epitaxial semiconductormaterial may introduce p-type dopants to the material being formedduring the epitaxial deposition process that includes p-type sourcegasses. As used herein, “p-type” refers to the addition of impurities toan intrinsic semiconductor that creates deficiencies of valenceelectrons. In a type IV semiconductor, such as silicon, examples ofp-type dopants, i.e., impurities, include but are not limited to, boron,aluminum, gallium and indium. The p-type gas dopant source may includediborane (B₂H₆). In some embodiments, the epitaxial deposition processfor forming the epitaxial semiconductor material for the source anddrain regions 65 a, 65 b may continue until the epitaxial semiconductormaterial that is formed on adjacent fin structures contact one anotherto form merged epitaxial semiconductor material. As used herein,“n-type” refers to the addition of impurities that contributes freeelectrons to an intrinsic semiconductor. In a type IV semiconductor,such as silicon, examples of n-type dopants, i.e., impurities, includebut are not limited to antimony, arsenic and phosphorous.

It is noted that the above process sequences describe a gate firstprocess sequence for forming FinFETs. The present disclosure is notlimited to only gate first processing. For example, gate last, which isalso referred to as replacement gate processing, is also suitable foruse with the methods and structures of the present disclosure. A gatelast process can include forming a replacement gate structure on thechannel portion of the fin structures, forming a spacer on the sidewallof the replacement gate structure, forming source and drain regions onopposing sides of the replacement gate structure, removing thereplacement gate structure, and forming a functional gate structure inthe space once occupied by the replacement gate structure. Thereplacement gate structure can include sacrificial material that definesthe geometry of a later formed functional gate structure that functionsto switch the semiconductor device from an “on” to “off” state, and viceversa. A process sequence employing a replacement gate structure may bereferred to as a “gate last” process sequence. Both gate first and gatelast process sequences are applicable to the present disclosure.

The methods and structures that have been described above with referenceto FIGS. 1-21B may be employed in any electrical device includingintegrated circuit chips. The integrated circuit chips including thedisclosed structures and formed using the disclosed methods may beintegrated with other chips, discrete circuit elements, and/or othersignal processing devices as part of either (a) an intermediate product,such as a motherboard, or (b) an end product. The end product can be anyproduct that includes integrated circuit chips, including computerproducts or devices having a display, a keyboard or other input device,and a central processor.

Having described preferred embodiments of a methods and structuresdisclosed herein, it is noted that modifications and variations can bemade by persons skilled in the art in light of the above teachings. Itis therefore to be understood that changes may be made in the particularembodiments disclosed which are within the scope of the invention asoutlined by the appended claims. Having thus described aspects of theinvention, with the details and particularity required by the patentlaws, what is claimed and desired protected by Letters Patent is setforth in the appended claims.

What is claimed is:
 1. A semiconductor device comprising: a firstplurality of fin structures in a first device region and a secondplurality of fin structures in a second device region, wherein the firstplurality of fin structures includes adjacent fin structures separatedby a lesser pitch than the adjacent fin structures in the secondplurality of fin structures; and at least one layer of dielectricmaterial between said adjacent fin structures in the first plurality offin structures in the first device region and the second plurality offin structures in the second device region, wherein a portion of thefirst plurality of fin structures extending above the at least one layerof dielectric material in the first device region is substantially equalin height to a portion of the second plurality of fin structuresextending above the at least one layer of dielectric material in thesecond device region.
 2. The semiconductor device of claim 1, whereinthe first plurality of fin structures are separated by a first pitchranging from 10 nm to 100 nm.
 3. The semiconductor device of claim 1,wherein the second plurality of fin structures are separated by a secondpitch ranging from 100 nm to 1000 nm.
 4. The semiconductor device ofclaim 1, wherein said at least one layer of dielectric material that ispresent between said adjacent fin structures in the second plurality offin structures comprises a buried etch stop layer.
 5. The semiconductordevice of claim 4, wherein the buried etch stop layer comprises anitride.
 6. The semiconductor device of claim 5, wherein the nitride issilicon nitride.
 7. The semiconductor device of claim 6, wherein theburied etch stop layer has a conformal thickness.
 8. A structurecomprising: a first plurality of fin structures in a first device regionand a second plurality of fin structures in a second device region,wherein the first plurality of fin structures includes adjacent finstructures separated by a lesser pitch than the adjacent fin structuresin the second plurality of fin structures; and at least one layer ofdielectric material between said adjacent fin structures in the firstplurality of fin structures in the first device region and the secondplurality of fin structures in the second device region, wherein aportion of the first plurality of fin structures extending above the atleast one layer of dielectric material in the first device region has aheight that is greater than the first plurality of fin structures. 9.The structure of claim 8, further comprising a gate structure on achannel region of at least one of said first plurality of fin structuresand at least one of said second plurality of fin structures.
 10. Thestructure of claim 8, wherein the first plurality of fin structures areseparated by a first pitch ranging from 10 nm to 100 nm.
 11. Thestructure of claim 8, wherein the second plurality of fin structures areseparated by a second pitch ranging from 100 nm to 1000 nm.
 12. Thestructure of claim 8, wherein said at least one layer of dielectricmaterial that is present between said adjacent fin structures in thesecond plurality of fin structures comprises a buried etch stop layer.13. The structure of claim 12, wherein the buried etch stop layercomprises a nitride.
 14. The semiconductor device of claim 12, whereinthe nitride is silicon nitride.
 15. The semiconductor device of claim14, wherein the buried etch stop layer has a conformal thickness.
 16. Asemiconductor device comprising: a first plurality of fin structures ina first device region and a second plurality of fin structures in asecond device region, wherein the first plurality of fin structuresincludes adjacent fin structures separated by a lesser pitch than theadjacent fin structures in the second plurality of fin structures,wherein an upper surface of the second plurality of fin structures issubstantially coplanar with an upper surface of the first plurality offin structures; and at least one layer of dielectric material betweensaid adjacent fin structures in the first plurality of fin structures inthe first device region and the second plurality of fin structures inthe second device region, wherein a portion of the first plurality offin structures extending above the at least one layer of dielectricmaterial in the first device region is substantially equal in width to aportion of the second plurality of fin structures extending above the atleast one layer of dielectric material in the second device region. 17.The semiconductor device of claim 16, wherein the first plurality of finstructures are separated by a first pitch ranging from 10 nm to 100 nm.18. The semiconductor device of claim 17, wherein the second pluralityof fin structures are separated by a second pitch ranging from 100 nm to1000 nm.
 19. The semiconductor device of claim 16, wherein said at leastone layer of dielectric material that is present between said adjacentfin structures in the second plurality of fin structures comprises aburied etch stop layer.
 20. The semiconductor device of claim 19,wherein the buried etch stop layer comprises a nitride.